Re: Device loses barrier support (was: Fixed patch for simple barriers.)

From: Andi Kleen
Date: Thu Dec 04 2008 - 19:37:51 EST

> And if barriers fail at random points, the user can't turn on disk cache
> anyway (he would get data corruption if barrier write failed and hardware

I think we already established earlier in the thread that there is no disk

> > > I'm wondering, where in fsync() does Linux wait for hardware disk cache to
> > > be flushed? Isn't there a bug that fsync() will return before the cache is
> > > flushed? I couldn't really find it. The last thing do_fsync calls is
> > > filemap_fdatawait and it doesn't do cache flush (blkdev_issue_flush).
> >
> > At least in fsync() on journaling fs the metadata update should push it.
> >
> > -Andi
> And what about fdatasync()?

I don't know. The surest way to find out is to instrument it and try.

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